Hi I would to install OpenOS and this need pastebin and this don`t working

You need an Internet card and somewhere to write to use the pastebin utility included with OpenOS (eg. an HDD). Please verify these points and include more details (what kind of computer/server/robot you are using in-game, the version of the game and OpenComputers...).

You have to use the pastebin program to install MineOS, not OpenOS. To install OpenOS, once booted up with a floppy disk containing OpenOS, simply type install in the prompt. Then follow the instructions on screen.

And than came the error if I want to run the Pastevin command

I used the version from ATM3 Minecraft Version 1.12 and Computer TIER 3 with a Internet Card and I want to install OpenOS wirh the Command and than this say can not find this by Pastebin

What error ?
if it says no error and a stacktrace, that's a duplicate of #3769 and you have to download the new 1.8.8 update of the mod (or tell the author of the modpack)

i believe the ATM creators disable OpenComputers internet access (or at least for CC) in the config by default. not something fixable by OC unless it's actually a different issue.

To test if this is true he could try the wget method that retrieve from GitHub. If Internet access is blocked, it wouldn't work whereas if it works then it's a duplicate of #3769. The author of the modpack could block Internet access on the server pack and enable it on the client pack, though.

No response in almost two months; I can't fix something that I cannot clearly reproduce.